Statistical Studies: Standard Deviation (Assignment) ~amdm

1. A contractor records the areas, in square feet, of several houses in a neighborhood to determine data about the neighborhood. They are: 2,400; 1,750; 1,900; 2,500; 2,250; 2,100 Which of the following represents the numerator in the calculation of variance and standard deviation? 2. What is the variance? 3. What is the standard deviation, rounded to the nearest whole number?

1. (250)2 + (-400)2 + (-250)2 + (350)2 + (100)2 + (-50)2 = 420,000 2. 84000 3.290

A contractor records all of the bedroom areas, in square feet, of a five-bedroom house as: 100, 100, 120, 120, 180 1. What is the variance? 2. What is the standard deviation?

1. 864 2. 29.4

1. A data set has the following characteristics: Mean: 4.9 Median: 6 Mode: 6 Variance: 4 The z-score is the number of 2. a data value is away from the Using the formula below, calculate the z-score for the listed data points. 3. z1= 4. z5= 5. z6.5=

1. standard deviations 2. mean 3. -1.95 4. 0.05 5. 0.8

1. The data set on the right represents 2.Which formula should be used to calculate the variance? 3. What is the variance?

1. the population 2. C 3. 58.5

The data value x exists in two data sets: A and B. The mean is equal for both data sets. If the standard deviation for set A is greater than the standard deviation for set B, which is true for zx for set A?

It is less than zx for set B.

A contractor records the areas, in square feet, of several houses in a neighborhood to determine data about the neighborhood. Which formula should be used to calculate the standard deviation? Why does the formula use "n - 1" in the denominator?

The second formula The data is a sample and is expected to be more dispersed from the mean.

Given that z20 = -2 and z50 = -1, which of the following do you know?

The standard deviation is 30. The mean is 80. The data point x = 20 is 2 standard deviations from the mean. The data point x = 50 is 1 standard deviation from the mean.

A set of data has a high-value outlier. How do you expect the standard deviation to change when the outlier is removed? Would the result be different if the data had a low-value outlier instead? Explain.

What to include in your response. The standard deviation will decrease when the outlier is removed. Standard deviation represents the spread of data from the mean. Removing a high-value outlier decreases the spread of data from the mean. Removing a low-value outlier decreases the spread of data from the mean. In both cases the standard deviation decreases.